README.md

Chef Provisioning

Overview

Chef Provisioning is a Cookbook and Recipe based approach for managing your infrastructure. Users can codify their infrastructure and use Chef to converge their infrastructure to the desired state. It has a plugin model (called Drivers) to manage different infrastructures, including AWS, Azure and Fog.

Target Audience

Chef Provisioning is a good fit for people who use or want to use the Chef ecosystem to manage their infrastructure. Infrastructure is represented as Chef Resources and managed in Chef Recipes and Cookbooks. These recipes run on a provisioner node and attempt to converge the infrastructure idempotently. The AWS driver is the most used, the most tested and receives the most updates.

Chef Provisioning and its Drivers are maintained by the open source community. They currently have a slow tempo for issue triage and pull request merging. Troubleshooting a bug may require stepping through the Ruby Chef codebase and engaging the community.

If you are new to Chef and Chef Provisioning, learning both can be daunting. If you are not familiar with Ruby as well, double the learning curve. Successful provisioning users know how they want to manage their cookbooks. Generally this is some CI/CD pipeline.

Chef is very flexible which allows customized provisioning solutions at the cost of high complexity. This makes it hard to document all the possible use cases. Patterns (for example, how to manage the provisioning node and run the provisioning recipes) are not well documented.

Chef Provisioning should be used to manage infrastructure (CRUD operations) and register Chef nodes with the server for the first time only. Other use cases (like scheduling chef runs, node inventory or reporting) are not supported.

Documentation

These are the primary documents to help learn about using Provisioning and creating Provisioning drivers:

This will create two vagrant precise64 linux boxes, "mario" and "luigi1", in ~/machinetest, bootstrapped to an empty runlist. For Windows, you can replace myapp::linux with myapp::windows, but you'll need your own Windows vagrant box to do that (licensing!).

AWS

If you have an AWS account, you can spin up a machine there like this:

export CHEF_DRIVER=aws
chef-client -z simple.rb

This will create two linux boxes in the AWS account referenced by your default profile in ~/.aws/config (or your environment variables).

DigitalOcean

If you are on DigitalOcean and using the tugboat gem, you can do this:

export CHEF_DRIVER=fog:DigitalOcean
chef-client -z simple.rb

If you aren't using the tugboat gem, you can put driver and driver_options into your .chef/knife.rb file.

This will use your tugboat settings to create whatever sort of instance you normally create.

Cleaning up

When you are done with the examples, run this to clean up:

chef-client -z destroy_all.rb

What Is Chef Provisioning?

Chef Provisioning has two major abstractions: the machine resource, and drivers.

The machine resource

You declare what your machines do (recipes, tags, etc.) with the machine resource, the fundamental unit of Chef Provisioning. You will typically declare machine resources in a separate, OS/provisioning-independent file that declares the topology of your app--your machines and the recipes that will run on them.

The machine resources from the cluster.rb example are pretty straightforward. Here's a copy/paste:

You will notice the dynamic nature of the number of web servers. It's all code, your imagination is the limit :)

Drivers

Drivers handle the real work of getting those abstract definitions into real, physical form. They handle the following tasks, idempotently (you can run the resource again and again and it will only create the machine once--though it may notice things are wrong and fix them!):

Acquiring machines from the cloud, creating containers or VMs, or grabbing bare metal

Connecting to those machines via ssh, winrm, or other transports

Bootstrapping chef onto the machines and converging the recipes you suggested

The driver API is separated out so that new drivers can be made with minimal effort (without having to rewrite ssh, tunneling, bootstrapping, and OS support). But to the user, they appear as a single thing, so that the machine acquisition can use its smarts to autodetect the other bits (transports, OS's, etc.).

Drivers save their data in the Chef node itself, so that they will be accessible to everyone who is using the Chef server to manage the nodes.

Machine options

You can pass machine options that will be used by machine, machine_batch and machine_image to
configure the machine:

require 'chef/provisioning/vagrant_driver' is how we bring in the vagrant_box resource.

vagrant_box makes sure a particular vagrant box exists, and lets you specify machine_options for things like port forwarding, OS definitions, and any other vagrant-isms.

Typically, you declare these in separate files from your machine resources. Chef Provisioning picks up the drivers and machine_options you have declared, and uses them to instantiate the machines you request. The actual machine definitions, in this case, are in simple.rb, and are generic--you could use them against Azure or EC2 as well:

machine 'mario'do
tag 'itsame'end

Other directives, like recipe 'apache', help you set run lists and other information about the machine.

Pointing Boxes at Chef Servers

By default, Chef Provisioning will put your boxes on the same Chef server you started chef-client with (in the case of -z, that's a local chef-zero server). Sometimes you want to put your boxes on different servers. There are a couple of ways to do that:

with_chef_local_server :chef_repo_path => '~/repo'

with_chef_local_server is a generic directive that creates a chef-zero server pointed at the given repository. nodes, clients, data bags, and all data will be stored here on your provisioner machine if you do this.

You can use with_chef_server instead if you want to point at OSS, Hosted or Enterprise Chef, and if you don't specify a Chef server at all, it will use the one you are running chef-client against. Keep in mind when using with_chef_server and running chef-client -z on your workstation that you will also need to set the client name and signing key for the chef server. If you've already got knife.rb set up, then something like this in the provisioning recipe will correctly create a client for the chef server on instance using your knife.rb configuration:

Finally, you can specify a Chef Server for an individual machine by using the chef_server attribute. This attribute takes the same additional options (:client_name, :signing_key_filename) that with_chef_server does.

Configuring ACLs

If you want to run your provisionning recipes from an actual chef node, rather than from your workstation, you need to give that node's client enough rights to create the node and client he'll be provisioning on the chef server. Without those additional rights, the provisioning will fail with a error along the lines of chef_client[mymachine] had an error: Net::HTTPServerException: 403 "Forbidden".

A clean solution to this problem is to use knife-acl to define a provisioners group with the required rights, and add your client to it: